This invention relates to the preparation of a plastic modified inscribing writing, or drawing composition which when applied to a suitable surface may subsequently be spread by means of water or other solvents.
Various writing or inscribing compositions are known in the art, for example wax and oil pastels, which have been employed for many years. Such wax and oil pastels have been manufactured by extruding or casting into appropriate shapes a composition containing color pigments, filler, and different waxes. Classical writing implements are also known, sometimes being called "Progresses" and being understood to be a core of writing composition such as those aforementioned and having a thin protecting coat thereon. Classical Progresses have been prepared by forming compositions of color pigments, fillers, and bonding agents soluble in water, such compositions being homogenized in suitable equipment as for example kneading mills and subsequently formed into the desired shape by extrusion, compression, and related techniques. Such shaped compositions have been treated after drying by impregnation in a molten composition of waxes and may have been further wetted in different lacquers in order to modify the surface characteristics, thereof.
In contrast to the compositions of the instant invention, however, the prior art compositions could not successfully be employed in such manner that permitted spreading of the tracing or drawing by means of solvents, particularly by means of water. The term "spreading", as used herein means the characteristic ability to extend or diffuse the tracing of the composition, subsequent to applying same to a surface, beyond the original configuration of the tracing. Spreading can be achieved by means of a brush, a sponge or the like using a suitable solvent such as water or various organic solvents. When applied to substrates or surfaces such as paper, parchment, wood, fabric the tracing composition may be expanded to produce a larger color area or to obtain color changes and shading by diffusing one color into another. When the instant compositions are applied to glass-like or plastic substrates, various organic solvents may be utilized which, in addition to spreading the tracing, may also otherwise spread or diffuse the plastic substrate, often resulting in further pleasing color relationships.